The present disclosure relates to a liquid crystal display panel and a manufacturing method thereof, and particularly relates to a liquid crystal display panel manufactured with sealing material being applied (written or painted).
A liquid crystal display panel includes a pair of substrates arranged so as to oppose each other; a liquid crystal layer provided between such substrates; and sealing material for bonding the substrates to each other, and for sealing the liquid crystal layer.
For example, Japanese Patent Publication No. 11-44869 describes a method for manufacturing a strong liquid crystal display panel having a good cutting surface by simultaneously cutting sealing material and a pair of glass substrates with the sealing material being interposed between the pair of substrates.
Recently, in a manufacturing process of liquid crystal display panels, a one-drop-filling method with higher productivity than that of a conventional dipping injection method has been frequently used as a method for sealing a liquid crystal layer between a pair of substrates. In such a one-drop-filling method, e.g., after applying sealing material in a frame-like shape on a surface of one of a pair of substrates, and dispensing liquid crystal material onto the substrate surface within the frame defined by the sealing material, such a substrate is bonded to another substrate. As a method for dispensing sealing material onto a substrate surface, a method in which, while discharging sealing material from a nozzle tip, a substrate or nozzle is moved has been frequently used.
Liquid crystal display panels have been often manufactured by a so-called “gang printing” in which a single glass substrate is divided and cut into a plurality of cell units. There is a method for cutting a pair of glass substrates on sealing material as described in Japanese Patent Publication No. 11-44869, in which, e.g., sides of sealing materials of adjacent cell units laterally contact with each other to be integrated, and such wide sealing material and a pair of glass substrates are cut at an intermediate position in the width direction of the sealing material.
However, considering non-uniformity of the width of the applied sealing material, there is a possibility that distortion of a cutoff line and reduction in moisture resistance are caused as described later.
FIGS. 6 and 7 are cross-sectional views of portions between cells in multi-sectioned bonded bodies 130a and 130b formed as the above-described pair of substrates by bonding TFT (thin film transistor) mother substrates 110a and 110b to color filter mother substrates 120 with liquid crystal layers 115 being interposed therebetween.
As illustrated in FIG. 6, the TFT mother substrate 110a includes a glass substrate 111; a plurality of TFTs (not illustrated in the figure) provided on the glass substrate 111; a resin film 112a provided so as to cover the TFTs; a plurality of pixel electrodes 113 arranged in a matrix on the resin film 112a; and an alignment film 114a provided so as to cover the pixel electrodes 113. The TFT mother substrate 110b has substantially the same structure as that of the TFT mother substrate 110a, except that a resin film 112b and an alignment film 114b are provided on the entire substrate as illustrated in FIG. 7. As illustrated in FIGS. 6 and 7, the color filter mother substrate 120 includes a glass substrate 121; a color filter layer 122 which is provided on the glass substrate 121, and contains colored layers 122a and a black matrix 122b; photo spacers 123 provided on the color filter layer 122; a common electrode 124 provided so as to cover the color filter layer 122; and an alignment film 125 provided so as to cover the common electrode 124.
As illustrated in FIGS. 6 and 7, in the bonded bodies 130a and 130b, the TFT mother substrates 110a and 110b are bonded to the color filter mother substrates 120 with sealing materials 126 being interposed therebetween. However, a space 127 may be formed between sides of the adjacent sealing materials 126.
Such a space 127 may be formed due to non-uniformity of the width of the applied sealing material 126. FIG. 8 is a schematic view from above, which illustrates the sealing material 126 in a bonded body 130 equivalent to the bonded bodies 130a and 130b. FIGS. 9 and 10 are IX-IX and X-X cross-sectional views of the bonded body 130 of FIG. 8. In FIG. 8, a chain double-dashed line represents a side edge position of the sealing material 126 upon applying the sealing material 126.
After linearly applying the sealing material 126, e.g., so as to form a plurality of frames on the color filter mother substrate 120, the color filter mother substrate 120 is bonded to the TFT mother substrate 110, thereby spreading the sealing material 126 in the width direction as illustrated in FIG. 8. As illustrated in FIGS. 8 and 10, in wider portions of the sealing materials 126, the sides of the adjacent sealing materials 126 contact and are integrated with each other to be fixed. On the other hand, in narrower portions of the sealing materials 126, even if the narrower portions are processed for the same period of time as that for the wider portions, the sides of the adjacent sealing materials 126 are fixed with the sides not contacting with each other as illustrated in FIGS. 8 and 9. The space 127 tends to be formed between the sides of the adjacent sealing materials 126 in the narrower portions of the sealing materials 126. Consequently, when the bonded body 130 is cut into cell units with a cutting blade 140, it is difficult to vertically apply a pressure from a blade edge of the cutting blade 140 on a substrate surface due to the space 127 present below the blade edge of the cutting blade 140. Hence, a scribe line (crack) is not vertically formed with respect to the substrate surface, thereby possibly causing the cutoff line distortion. Even if the scribe line is vertically formed with respect to the substrate surface, and the bonded body 130 is vertically cut with respect to the substrate surface as illustrated in FIG. 11, the cut bonded body 130, i.e., a liquid crystal display panel 150 has a cutting surface formed with a gap 127a due to the space 127 of the bonded body 130. Hence, an effective width of a sealing material 126a becomes narrower in such a portion, thereby possibly reducing the moisture resistance of the liquid crystal display panel 150.
The present disclosure has been made in view of the foregoing, and it is an object of the present disclosure to stabilize formation of the straight cutoff line of the liquid crystal display panel, and to reduce the degradation in the moisture resistance.